Vapor electric device



Nov. 12, 1935. E. H. REID 2,920,962

VAPQR ELECTRIC DEVICE Original Filed May 20, 1930 2 Sheets-Sheet 1 Inventor: Eugene HRead;

ac/ 6M Nov. 12, 1935. E. H. REID.

I VAPOR ELECTRIC DEVICE Ofiginai Filed May 20. 1930 2 Sheets-Sheet 2 In ventof:

Eugene Reid;

m His Attorney.

Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE VAPOR ELECTRIC DEVICE Eugene H. Reid, Schenectady, N. Y., assignor to General Electric Company, a. corporation of New York 1932, Serial No. 620,219

2 Claims.

This application is a division of my application Serial No. 454,142 filed May 20, 1930 and assigned to the same assignee as the present application.

My invention relates to vapor electric devices J for transmitting current between direct and alternating current systems, and has for its object the provision of an improved device of this character which is of high load capacity and of increased efficiency and reliability in operation.

1Q A feature of my invention is the provision of an improved temperature regulating means for the anode region of a mercury arc device. In the operation of power mercury are devices it is well known that the anodes and parts adjacent thereto must be maintained at a temperature above the condensing temperature of the mercury vapor in the device, thus preventing the occurrence, in the region adjacent the anodes, of high vapor pressure which would otherwise be present by reason of the revaporizing of mercury which is condensed during the idle periods of the device. Electric heater means employed heretofore for the above described purpose have the disadvantage that they require appreciable power and provide adequate temperature control over only a small part of the anode region. In accordance with my invention these disadvantages are avoided by the provision of improved means to maintain the'housings in which the anodes are mounted immersed in a body of stagnant temperature controlling medium.

Another feature of the present invention is the provision of an improved sealing means between cooperating sealing surfaces in the mercury arc device. Difficulties have been encountered heretofore in forming tight seals at various points therein, particularly between the anode housings and cover members therefor. Heretofore gaskets of soft metal such as aluminum have been used, two of such gaskets or rings being mounted between the cooperating sealing surfaces and the rings being retained in position by grooves formed in one of the surfaces. In operation relative motion of the surfaces dueto alternate heating and cooling has resulted in leakage at the seal. In accordance with my invention the above disadvantage is avoided by the provision of a gasket of soft elastic material such as rubber mounted between the metal gaskets. A further feature of my inventionis the provision of improved means for control of the arc discharge in mercury are devices and for pre- 5 vention of arc-back therein. Difficulties have been encountered in the control of the are discharge between cathode and anode, the control electrode provided therefor proving inadequate in certain cases. These difliculties are avoided by providing that the control electrode is mount- 5 ed between the anode and a member which functions as an auxiliary control means and which is constituted by an anode baffle member through which the arc discharge passes before reaching the control electrode.

A further feature of my invention is the provision of an improved insulating means for the control electrode. Difiiculties in the insulating of the control electrode have been encountered heretofore especially in high power mer- 15 cury are devices, by reason of the exposure of the control electrode insulating member to extremely high temperature, with consequent coating of the insulating surface by decomposition products. In accordance with my invention 20 these difiiculties are avoided by mounting the control electrode insulator at a point within the anode housing remote from the tip of the anode; by connecting the insulator to the cover of the housing, this cover or end portion being im- 25 mersed in temperature controlling medium; and by providing a shield member mounted between the insulator and the anode to protect the insulator from the blast of the arc stream.

A further feature of the invention is the pro- 30 vision of improved means for removing impurities from the mercury which is-returned to the cathode after being condensed from the mercury vapor rising from the cathode. In the operation of mercury are devices difiiculties have been 35 encountered in the use of mercury straining devices, for example, short circuits have occurred due to the accumulation of trash or residue in spaces closely adjacent the active surface of the mercury cathode.

distance sufficiently remote from the cathode active surface to prevent arcing.

My invention will be better understood from the following description when considered in connection'with the accompanying drawings, and 50 its scope will be pointed out in the appended claims.

Referring to the drawings, Fig. 1 is a sectional view of a mercury arc device embodying my invention;

In accordance with the pres- 40 ent invention these difficulties are overcome by Fig. 2 is a cross sectional view of a portion of Fig. 1;

V Fig. 3 is a sectionaldetailed View of a vacuum.

seal; 7

Fig. 4 is a perspeotive'view of an anode loafile member;

Figs. 5 and 6 are fragmentary sectional views showing modifications of a mercury strainer.

In Figs. 1 and 2 is shown aimercury' arc device I I] which comprises casing members I I, I2 and which is surrounded by a temperature controlling "medium I3 contained in a'chamber I4. A vapor cooling dome I 5 may be provided having a casing member I6 extending upwardly from casing member II and surrounded by cooling medium I] contained in chamber I 8. In order to pro-.

vide further vapor cooling means a coil'of pipe I9 through which cooling medium is circulated.

may be mounted'within the dome. Temperature controlling medium I3 is admitted to chamber I4 through openings ZIl and discharged therefrom through openings 2|. Similarly, openings 22 and 23 are theadmission and dischargeopenings respectively for cooling fluid in chamber I8. The

imercury arc device further comprises amercury 'cathod'e 24contained in a cathode receptacle 25,

and a' plurality of main anodes 26 and holding anodesZl. Only one of each of the main anodes and holding anodes is shown in order to simplify The cathode receptacle 25 is consuitable insulating material. To maintain the cathode spot within the required area upon the surface of the mercury a quartz cylinder 3I is provided, the lower edge of this cylinder being immersed in the mercury.

Anode26 is mounted on the cover member 32 of an anode housing 33 which is weldedto the rectifier casing member II.

thermally insulated walls 35- which are 7 provided. with only a small opening or openings 36 for communication'withchamber I4.

. Those portions of'the anode housings which project above the casing I I are immersed in the substantially stagnant temperature controlling .me-

dium I3 contained within compartment 34. The

medium in this separate compartment absorbs the heat loss of the anodes during operation periods and stores the heat for the periods when 7 the mercury arc device is not running or is under 7 6:0

. of water or other temperature controlling melight load. During operating periods the body dium in compartment 34 rises-to and remains at a tenffierature sufficiently high toinsure that the surfaces. within the anode region, on whichmer- .cury vapor tends to condense, are maintained at a temperature above the condensing temperature "of the vapor. r V

Anode housing 33 is provided with a flange 31; the. upper surface of this flange andth'e surface I 3 8 at the lower edge of housing cover 32 'form' cooperating sealing surfaces between which are mounted deformable metal rings or hoop rings 39." These rings lie'in grooves 40 formed in the lower sealing surface. Clamping members" 4| and locking screws 42 are provided todraw the seal- The anode housings'are within a compartment 34 separated in accordance with the invention from cooling chamber. I4Iand from cooling chamber I8 by l sulator and the anode,"

ing members together and' thereby to press and flatten the metal rings to form a seal. In order to prevent loosening of the seal and subsequent leakage due to sliding of the smooth upper sealing surface 38 over the flattened rings 39 mount- 5 e r ed in; the grooves ;40, I provide in' accordance with my invention, an additional sealing means constitutedby a member of soft elastic material such as a' rubber ring 43 mounted between. the metal 7 rings 39. It will be seen that the two metal gas- 10 kets or hoop rings 39 form a pocket, andas the sealing surfaces 31, '38' are brought closer 'to-. gether by screws 42 the space'between the metal casings decreases, so that the. rubber ring 43 is pressed laterally as well as-vertically; The rub- 15- 'ber is thereby forced to spread under the edges of the metal gaskets39 and is sealed to the seal- .ing surfaces 3'! and 38, thus preventing seepage over these surfaces. Further, during the process .of bake-out ofthe mercury arc device by heavy 20 current the rubber ring is partially vulcanizedto the sealing surfaces and to the metal rings, thus forming a still more effective seal. During this bake-out process and subsequently. during op.-

erati'onof the mercury arc device the rubber is 25 protected from damage due to hightempe'rature by reason of 'the'factthat the seal is covered by the temperature controlling medium contained in compartment 34.. a

' Control means for the arc discharge in there-56 V tifier include a control electrode 44 and an anode 7 bafile' member. 46 comprising three concentric rings of steel or other suitable material. The control electrode includes the grid. member 45.

It will be observed that in accordance with my in- 35 1 V yention the arrangement of anode; control electrode and battle is such that the control electrode is mounted between the tip 411): the anode and the baffle 46. This arrangement of the baffle in the are discharge path is essential to adequate 4o V lCOIltIOl of the are by the control' electrode and to operation of the mercury arc device at vapor pressures varying to'such a degree as would oth erwise cause interruption of operation of thehde vice. The baffle 46 is secured by. welding or other- 4 'wise to the anode housing '33 in, the lower end thereof. I a

. The grid member .45 is'formed of molybdenum orother suitable wire and is mounted within-a cylinder 48 which'may ficomprise. a lower cylinder 5t) of molybdenum. surrounding the tip .41 of the anode and an upper cylinder 5!] of steel. In order .to avoid difficulties heretofore encountered due. to

exposure of the control electrode insulating means to extreme heat, theinsulator 5| for the I 7 control electrode is mounted, in accordance with 'jthe inve'ntion, in the upper portion of the anode housing ancLther'efore remote fr om the hottest portion of the anode. The insulator is mounted a 'on the housing cover 32as by' screws 52 and cylinder'50 is securedto theinsulator. The control electrode 44 comprising grid member 45 mounted within'cylinder 49 is thereforesuspended from the insulator 5|. For the further protection .of this insulator from excessive heat and from the blast of the arc discharge I provide a shield '53 V mounted on cover member 32 and between the in- 'A- mercu y strainer or impurity removin meansin accordance with my invention is shown r in Fig. 2 and comprises .a troughmemberfl whichis mounted on casing member 'IB'of dome V 15 adjacent the lower end thereof. Liquid mer cury condensed from mercury vapor entering the dome fiowsfromthe trough 54 into astrainer rte-" ceptacle 55 and thence through openings 56 into asecond strainer receptacle placed within receptacle 55. From receptacle 5! the mercury overflows into a discharge pipe 58. Pipes 59 conduct the mercury to the lower wall of the mercury arc device from which point the mercury returns to the cathode. Since the trash or residue in the mercury is always of lower specific gravity than the mercury, it is retained in receptacle 55 and thereby prevented from passing back to the oathode. In the modification of the mercury strainer shown in Fig. 5 the strainer comprises recep tacles 60 and 6| formed by a trough shaped member 62 of inverted V section having a partition member 63, and mounted upon the lower portion of casing member II. The liquid mercury condensed from mercury vapor within the mercury arc device flows down the casing member I into receptacle Bil which functions as a trough member to collect the mercury. From receptacle 60 the mercury passes through openings 64 in partition 53 into receptacle 6| from which it overflows through openings 65 in the trough member and thus returns to the cathode, the trash or residue being retained in receptacle B0. The modification of the mercury strainer shown in Fig. 6 is similar in construction and operation to that shown in Fig. 5. In the form shown in Fig. 6, however, strainer receptacles 66 and 6'! are formed by a trough member 68 of U section and a partition member 69 extending downwardly from casing member II. The partition member 69 may be formed as an extension of casing member H as shown in Fig. 6. The trough shaped member 68 extends downwardly into the a-nnul r space between quartz ring 3| and insulating ring 39 and is mounted upon casing member l2 by any suitable means. comprising trough member 68 is mounted close to the cathode ring 3|, the condensed mercury which flows down the lower wall of casing member II and over the lower edge thereof passes into receptacle t6, thence under partition 69 into the receptacle 6'! and overflows through openings it into the annular space between quartz ring 3i and insulating ring 30. The trash or residue from the mercury passing through the strainer is retained in receptacle 66. The inner wall I! of trough member 68 extends upwardly sufiiciently to prevent this residue accumulated in receptacle 68 from coming in contact with quartz ring 3 I.

It will be observed that in all the above described forms of the mercury strainer or trash gathering device the residue which is strained from the mercury is prevented from coming in contact with any portion of the mercury contained in the cathode receptacle L5 or with any portion of the insulation members 29, 3B, and 3|.

What I claim as new and desire to secure by Letters Patent of the United States is:

Since the strainer 1. In a vapor electric device comprising a casing member, a mercury cathode receptacle, a cathode ring member of refractory material immersed in the mercury within said receptacle,

a cylindrical insulating member mounted vacuum 5 tight between said casing and said receptacle, and a sleeve of insulating material between said cathode ring member and said cylindrical insulating member to separate the mercury of said cathode from said cylindrical member, means to strain impurities from mercury condensed within said device and to prevent contact of said impurities with said cathode ring, said means including a circular trough member of U section mounted out of the arc path in said device below said casing member and independently of and surrounding said cathode ring, and a circular partition member extending downwardly from said casing member and within the trough member, the outer wall of said trough member having overflow openings above the level of the lower end of said partition member, said sleeve of insulating material extending above the level of said outer wall of said trough, the inner wall of said trough member extending adjacent the cathode ring to a point sufficiently above the upper end of said partition member to prevent condensate which carries said impurities from coming in contact with said ring member.

2. In a vapor electric device comprising a casing member, a mercury cathode receptacle, a cathode ring member immersed in the mercury within said receptacle, a cylindrical insulating member mounted vacuum tight between said casing member and said receptacle and surrounding said cathode, and a cylindrical member of vitreous material mounted adjacent the inner surface of said cylindrical insulating member, a circular trough member of U section mounted out of the arc path in said device below said casing member in the space between the cathode ring member and independently of said ring member and said insulating member, said casing member having a portion extending downwardly from the main portion thereof to form a partition extend- 5 ing within said trough member, the outer wall of said trough member having overflow openings above the level of the lower end of said partition, said member of vitreous material extending from a point below the level of the mercury in said cathode to a point above the top of said cylindrical insulating member and of said outer wall of said trough member, the inner wall of said trough member extending adjacent to the outside wall of said cathode ring member to a point sufiiciently above the upper end of said partition member portion of the receptacle to prevent condensate which carries said impurities from coming in contact with said ring member and from flowing down the outside surface thereof into said annular space.

EUGENE H. REID. 

